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Are you sitting… well? About comfort,
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As a responsible of occupant comfort, we all have a duty to make a careful selection of appropriate diffusers and their proper positioning. We all want ensure high quality of comfort. For this, we must respect the requirements requested.
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Training on fast selection at 1.3 m / 30 fpm 2014, August Requirements by... The Canadian Standards Association
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5.3.1.1 The ventilation systems must satisfy ASHRAE 62 and 55 2014, August Training on fast selection at 1.3 m / 30 fpm
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« 5.3.2.1 b) the air blow should be introduced such that the speed of air movement, at the office workstation, are between 0.05 and 0.15 m/s. This is particulary crucial in the systems with variable air volume. » Note: Can be interpreted by « the office workstation », that it’s a situation where a person is seated and settled at 1.3 m above the ground. Note: Can be interpreted by « the office workstation », that it’s a situation where a person is seated and settled at 1.3 m above the ground. Training on fast selection at 1.3 m / 30 fpm 2014, August
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Thermal Environmental Conditions for Human Occupancy ANSI/ASHRAE Standard 55-2013 The requirements according… Training on fast selection at 1.3 m / 30 fpm 2014, August
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+3 Hot +2 Warm +1 Slightly Warm 0 Neutral -1 Slightly Cool -2 Cool -3 Cold Evaluation Criteria To be conform to Ashrea 55: PPD PMV Range <10 -0.5 <PMV < +0.5 Projected percentage of dissatisfied depending the average basis using the evaluation criteria ASHRAE, Standard 55-2013, p.23 Training on fast selection at 1.3 m / 30 fpm 2014, August
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Percentage of People Dissatisfied as Function of Mean Air Velocity Training on fast selection at 1.3 m / 30 fpm 2014, August
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OPERATIVE TEMPERATURE < 22.5˚C (72.5˚F) = MAXIMUM LIMIT = 0.15 m/s (30 fpm) ASHRAE, Standard 55-103, p.10 Training for fast selection at 1.3 m / 30 fpm 2014, August
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Operative Temperature< 22.5˚C (72.5˚F) = UPPER LIMIT= 0.15 m/s (30 fpm) ASHRAE, Standard 55-103, p.11 Training for fast selection at 1.3 m / 30 fpm 2014, August
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How to calculate the effective temperature : θ ed = (T x – T c ) – 0.07(V x – 30) (15) θ ed = (T x – T c ) – 8 (V x – 0.15) ASHRAE, Fundamentals Hanbook, 2009 Chapter 20 P.13 Note: When the air velocity is less than 30 fpm (0.15 m/s), the effective temperature is equal to the dry temperature. For this purpose, there isn't cold feeling by the air velocity. Training for fast selection at 1.3 m / 30 fpm 2014, August
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Training for fast selection at 1.3 m / 30 fpm 2014, August
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Training for fast selection at 1.3 m / 30 fpm 2014, August Percentage of occupants objecting to drafts in air-conditioned room AHREA, Fundamental Handbook, 2009, Chapter 20, p.13 ASHRAE SI (metric International System) ASHREA IP (Imperial System)
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Société Québécoise des infrastructures The requirements according… Training on fast selection at 1.3 m / 30 fpm 2014, August
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1.4.2 NOTE: Upper limit: 0,15 m/s at 21°C 1.4.2 NOTE: Upper limit: 0,15 m/s at 21°C 1.4.3 The room must to be conform of "Regulations on health and safety" and the requirements of ASHRAE (latest versions). 1.4.3 The room must to be conform of "Regulations on health and safety" and the requirements of ASHRAE (latest versions). Training on fast selection at 1.3 m / 30 fpm 2014, August
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Le Gouvernement du Québec Institutions of health and social services Guide de qualité de l’air intérieur dans les établissements du réseau de la santé et des services sociaux Training for fast selection at 1.3 m / 30 fpm 2014, August The requirements according…
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« Given that elderly are very sensitive to air currents, the selection of diffusers shall be made to ensure an air speed over 0.15 m/s in the occupied zone. The location of diffusers mustl also be determined with particular attention. » “La qualité de l’air intérieur dans les établissements du réseau de la santé et des services sociaux” Chapter 1, building design, page 37 « Given that elderly are also very sensitive to cold, the temperature of the airflow through the ventilation systems must be as close as possible to ambient room temperature to avoid discomfort » Notes: 1. If you have higher rate of induction at diffuser, this will reduce the temperature difference in area occupied; 2. The germans recommends that the limit of differential temperature should be the following ratio : ∆ T xy ∆ T 0 ≤ 0.1 Training for fast selection at 1.3 m / 30 fpm 2014, August
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The question to ask … Does the recommendations of the maximum air speed of 0.15 m / s (30 ppm), at a temperature of <22.5˚C for sedentary and sitting person is a must or a nice? Training for fast selection at 1.3 m / 30 fpm 2014, August
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What tools are available to help you to meet these requirements?
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NAD software Training for fast selection at 1.3 m / 30 fpm 2014, August
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560 cfm for the room So, 2 diffusers at 280 cfm Training for fast selection at 1.3 m / 30 fpm 2014, August
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Training for fast selection at 1.3 m / 30 fpm 2014, August
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Training for fast selection at 1.3 m / 30 fpm 2014, August
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Installation space between diffusers = 3.9 meters Space for each diffuser: 3.9 / 2 = 1.95 meters Training for fast selection at 1.3 m / 30 fpm 2014, August
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NAD Catalog Ceiling height =2.74 m High comfort level in a sitting position= 1.3 m Level required= 1.44 m Training for fast selection at 1.3 m / 30 fpm 2014, August
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Training for fast selection at 1.3 m / 30 fpm 2014, August Simplified Approach
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L – ( y = h – 1.3 ) V 0.15 X Training for fast selection at 1.3 m / 30 fpm 2014, August
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NAD Klima has prepared a simplified procedure. With the AutoCad program, create a layer that will be reserved for the air diffuser. This will allow you to clearly visualize, in a plan view, the air jet leaving the diffuser to the sitting position. This will help you to select the optimal size of diffusers and as their positioning in the design of the ventilation system. The following example gonna help you to understand this process. To meet the parameters of comfort in the occupied zone for an office zone, we have to base our design on a maximum air speed of 015 m / s (30 fpm) at a height of 1.3 meters above the ground. In this way, it will avoid for the occupants sitting, a cold feeling caused by the air stream. Training for fast selection at 1.3 m / 30 fpm 2014, August
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Training for fast selection at 1.3 m / 30 fpm 2014, August
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Training for fast selection at 1.3 m / 30 fpm 2014, August
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Training for fast selection at 1.3 m / 30 fpm 2014, August
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Training for fast selection at 1.3 m / 30 fpm 2014, August
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Training for fast selection at 1.3 m / 30 fpm 2014, August
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Training for fast selection at 1.3 m / 30 fpm 2014, August
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Training for fast selection at 1.3 m / 30 fpm 2014, August
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Training for fast selection at 1.3 m / 30 fpm 2014, August
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DAL 358 diffuser 3 ways DAL 358 diffuser 3 ways Training for fast selection at 1.3 m / 30 fpm 2014, August
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Autocad plan Training for fast selection at 1.3 m / 30 fpm 2014, August
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Training for fast selection at 1.3 m / 30 fpm 2014, August
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Training for fast selection at 1.3 m / 30 fpm 2014, August
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Training for fast selection at 1.3 m / 30 fpm 2014, August
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Place the cursor in the middle of the diffuser Training for fast selection at 1.3 m / 30 fpm 2014, August
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Enter the radius and click 'Enter' Training for fast selection at 1.3 m / 30 fpm 2014, August
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Training for fast selection at 1.3 m / 30 fpm 2014, August
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Double-clicking on the circle for open the small box. This confirm will that your radius is good. (8 * 12) + 10 = 106 inches Training for fast selection at 1.3 m / 30 fpm 2014, August
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Diffuser 3 way... How to make a half circle? Training for fast selection at 1.3 m / 30 fpm 2014, August
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The radius of the diffuser 3 way = The length of the radius DAL 358 X 1,3 106 x 1,3 = 137,8 r = 138 ‘’ Training for fast selection at 1.3 m / 30 fpm 2014, August
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Click on the tab “Line” to create the radius Training for fast selection at 1.3 m / 30 fpm 2014, August
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From the center of the diffuser, enter the desired radius and click 'Enter'; Repeat one more time (for the bottom radius); Don’t forget to be on Ortho mode. Training for fast selection at 1.3 m / 30 fpm 2014, August
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Length = 2 x radius Training for fast selection at 1.3 m / 30 fpm 2014, August
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1 2 3 Training for fast selection at 1.3 m / 30 fpm 2014, August
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Training for fast selection at 1.3 m / 30 fpm 2014, August
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Where are the problematic zones? Training for fast selection at 1.3 m / 30 fpm 2014, August
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? Training for fast selection at 1.3 m / 30 fpm 2014, August
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Click on the two desired areas, and click 'Enter' Training for fast selection at 1.3 m / 30 fpm 2014, August
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Here is the distance that will exceeds the comfort zone up to height of 1.3 m to 0.15 m / s (30 fpm) Training for fast selection at 1.3 m / 30 fpm 2014, August
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If you want to be conform of the requirements requested, just add a distance of 38"(2 X 19") between diffusers. Training for fast selection at 1.3 m / 30 fpm 2014, August
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Minimum parameters to considerate in the selection of air diffusers Summary selection parameters During the design stage and selection of air diffusers, it is advised to verify some parameters other than the diffusion of the air (see table). These parameters should be considered as criteria for approval the election of the air diffuser. They are considered to the maximum of the optimum range selection except for the critical “x” which is the minimum of the optimum. They are therefore evaluated once for a diffuser. Training for fast selection at 1.3 m / 30 fpm 2014, August
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Training for fast selection at 1.3 m / 30 fpm 2014, August
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Temperature ratio in occupied zone ( ∆T xy / ∆T o ) Training for fast selection at 1.3 m / 30 fpm 2014, August Curves of relative differential temperature European catalogs
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Training for fast selection at 1.3 m / 30 fpm 2014, August Cold air discharged horizontally in a room, as a result of the gravity, the air flow is low adheres to the ceiling and enters the occupied zone at high speeds. The distance between the diffuser outlet and the step the ceiling is called critical distance Xcrit To prevent cold air falls rapidly, the critical distance Xcrit must be at least 2 feet (0.6 m) for a maximum air flow. Critical distance Xcrit Curves as a function of the quality flow must be provided as this is the case of europeans manufacturers.
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Training for fast selection at 1.3 m / 30 fpm 2014, August
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Example with standard square cone diffuser Construction costs Per diffuser : Supply branch, hardware: Square cone diffuser: Labor: Balancing: 65 $ 32 $ 85 $ 30 $ Total : 212 $ Total x 6 : 1272 $ Training for fast selection at 1.3 m / 30 fpm 2014, August
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Example with high induction swirl diffuser of NAD Klima Construction costs Per diffuser : Supply branch, hardware: NAD diffuser: Labor: Balancing: 65 $ 134 $ 85 $ 30 $ Total : 314 $ Total x 4 : 1256 $ Training for fast selection at 1.3 m / 30 fpm 2014, August
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Now, you know the methods quick and simplified methods used by NAD Klima to meet the norms, standards and customer requirements.
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